On this page I am trying to collect a list of major email servers that ultilize greylisting in order to stop spam. If you know of any major users of greylisting that are not listed here, you are welcome to contact me (contact info on the about page).
SoftHome.net is one of the oldest specialized free / paid email providers on the internet today. Their service has been very reliable. They offer an email that can be accessed both via a webclient or pop3 (ie., from outlook). Their say about greylisting.
Sneakemail is a very useful "disposable" email service. In essence it is not a real email provider, rather it will let you set up email forwards to your real email address - to use, ie., when you sign up / give out your email address to someone you do not know. Their page about greylisting.
As is clear on this page the Norwegian university of Bergen is using greylisting on their mail server.
This Texas university is using greylisting: www.tamu.edu/network-services/smtp-relay/greylisting.html
RWTH is a large German University. They have a page on their greylisting (german) here: www.rz.rwth-aachen.de/infodienste/email/greylisting.php
This webhosting service has implemented blacklisting. I have received some feedback from some of their users - reporting a drastic decrease in spam received.
DAIMI is part of the University of Aarhus, Denmark. They use greylisting for something like 100,000 daily incoming messages and are reporting very good experiences with it. They have a FAQ: www.daimi.au.dk/local/greylisting.php
This is a major email ISP that is now officially using greylisting: mailsnare.net/forum/viewtopic.php?t=1563
This (www.tigertech.net/) greylisting user is using it for around 2,9 million mails/month. They are reporting great results, saving them lots of cash in bandwidth costs and stopping more than 1 million spam mails per month.
LRZ is a major German internet hub for academic institutions in southern Germany. They started using greylisting as a method of limiting spam a couple of months ago: www.lrz-muenchen.de/aktuell/ali2052/
Rollernet.Us provides secondary DNS, backup mail, SMTP redirection, SMTP filtering, and other DNS/MX based services. Their service now features greylisting: acc.rollernet.us/help.php#grey
This major Swedish unversity has used greylisting for some time now; nyteknik.se/art/39257
This organisation, one of the five major internet registries of the world, is also using greylisting: www.apnic.net/info/contact/greylisting.html
FastMail.FM is a major email service with thousands of clients (I use them myself), with a highly effective and fast webinterface. Since July 26th, 2006, they are now using greylisting; blog.fastmail.fm/?p=565
SPF is a large public access unix system, which is used by students and other people to explore and work with unix operating systems (in particular NetBSD). They have a page on greylisting: sdf.lonestar.org/index.cgi?faq?EMAIL?07
This large ISP is also using greylisting on their servers to limit spam: www.pair.com/support/knowledge_base/e-mail/enhanced_junk_e-mail_filtering_system_faqs.html#9
This (very energy minded) webhosting company now also supports greylisting: www.aiso.net/spam-protection.asp
This major factor in combatting spam worldwide, is also using greylisting in your mailing system: forum.spamcop.net/forums/index.php?showtopic=8650